1. Field of Invention
The present disclosure of invention relates to thin film transistor substrates such as used in flat panel displays and to a method of manufacturing such thin film transistor substrates. More particularly, the present disclosure relates to an organic thin film transistor (oTFT) substrate and a method of manufacturing the organic thin film transistor substrate in a manner capable of uniformly defining a thickness of a gate insulating layer and of a protective layer and of preventing or reducing overflow of an organic semiconductive layer which is used to form one or more oTFT's.
2. Description of Related Art
In general, liquid crystal displays (“LCDs”) display an image in such a way that liquid crystal containing cells arranged on a liquid crystal panel in a matrix selectively adjust light transmittance therethrough in accordance with supplied video signals.
Each liquid crystal cell includes a thin film transistor (“TFT”) used as a switching element for selectively supplying video signals to one or more charge-storing capacitor plates of that cell. An active layer of the TFT is conventionally composed of an amorphous-Si or a polycrystalline-Si.
Since the amorphous-Si or a poly-Si active layer is conventionally patterned and formed by one or more of a thin film deposition (coating) process, a photolithography process, and an etching process, there have been several problems including that the process tends to become complex and manufacturing costs rise.
Recently, research and development have focused on instead using an organic thin film transistor (oTFT) formed from an active layer comprising an organic semiconductive material which may be formed by a printing process.
Such an organic semiconductive layer of the organic thin film transistor (oTFT) typically needs to be protected by a protective layer which may be formed within a hole prepared in a border-defining insulating layer. Further, a gate line and a data line connected with the organic thin film transistor cross with each other and have a gate insulating layer interposed between them. Conventionally, an edge portion and a center portion of each of a gate insulating layer and a protective layer have different thickness, thereby generating an undesirable appearance of a spot at the point where the disparate thicknesses occur in unison. Further, a conventional organic semiconductive layer is not formed within a hole prepared by a border-defining insulating layer and thus the conventional organic semiconductor material tends to overflow out of the conventional containment hole.